pgo: Make chrome_pgo_phase have an effect on all files, not just files in the chrome target.

Bug: 1056189
Change-Id: Iee607dda6c4788d836115c53e43c5c93f63486a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2078426
Auto-Submit: Nico Weber <thakis@chromium.org>
Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745196}

build/config/BUILDCONFIG.gn

@@ -436,6 +436,7 @@ default_compiler_configs = [
   "//build/config/compiler:runtime_library",
   "//build/config/compiler:thin_archive",
   "//build/config/compiler:default_init_stack_vars",
+  "//build/config/compiler/pgo:default_pgo_flags",
   "//build/config/coverage:default_coverage",
   "//build/config/sanitizers:default_sanitizer_flags",
 ]

build/config/compiler/pgo/BUILD.gn

@@ -5,24 +5,22 @@
 import("//build/config/clang/clang.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/compiler/pgo/pgo.gni")
+import("//build/toolchain/toolchain.gni")
 
 # Configuration that enables PGO instrumentation.
 config("pgo_instrumentation_flags") {
   visibility = [ ":default_pgo_flags" ]
-  cflags = []
-  ldflags = []
 
   # Only add flags when chrome_pgo_phase == 1, so that variables we would use
   # are not required to be defined when we're not actually using PGO.
-  if (chrome_pgo_phase == 1) {
-    if (is_clang) {
-      cflags = [ "-fprofile-instr-generate" ]
-      if (!is_win) {
-        # Windows directly calls link.exe instead of the compiler driver when
-        # linking, and embeds the path to the profile runtime library as
-        # dependent library into each object file.
-        ldflags += [ "-fprofile-instr-generate" ]
-      }
+  if (chrome_pgo_phase == 1 && is_clang && use_lld && !is_nacl &&
+      is_a_target_toolchain) {
+    cflags = [ "-fprofile-instr-generate" ]
+    if (!is_win) {
+      # Windows directly calls link.exe instead of the compiler driver when
+      # linking, and embeds the path to the profile runtime library as
+      # dependent library into each object file.
+      ldflags = [ "-fprofile-instr-generate" ]
     }
   }
 }
@@ -30,25 +28,22 @@ config("pgo_instrumentation_flags") {
 # Configuration that enables optimization using profile data.
 config("pgo_optimization_flags") {
   visibility = [ ":default_pgo_flags" ]
-  cflags = []
-  ldflags = []
 
   # Only add flags when chrome_pgo_phase == 2, so that variables we would use
   # are not required to be defined when we're not actually using PGO.
-  if (chrome_pgo_phase == 2) {
-    if (is_clang) {
-      assert(pgo_data_path != "",
-             "Please set pgo_data_path to point at the profile data")
-      cflags += [
-        "-fprofile-instr-use=$pgo_data_path",
+  if (chrome_pgo_phase == 2 && is_clang && use_lld && !is_nacl &&
+      is_a_target_toolchain) {
+    assert(pgo_data_path != "",
+           "Please set pgo_data_path to point at the profile data")
+    cflags += [
+      "-fprofile-instr-use=$pgo_data_path",
 
-        # It's possible to have some profile data legitimately missing,
-        # and at least some profile data always ends up being considered
-        # out of date, so make sure we don't error for those cases.
-        "-Wno-profile-instr-unprofiled",
-        "-Wno-error=profile-instr-out-of-date",
-      ]
-    }
+      # It's possible to have some profile data legitimately missing,
+      # and at least some profile data always ends up being considered
+      # out of date, so make sure we don't error for those cases.
+      "-Wno-profile-instr-unprofiled",
+      "-Wno-error=profile-instr-out-of-date",
+    ]
   }
 }
 

chrome/BUILD.gn

@@ -4,7 +4,6 @@
 
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
-import("//build/config/compiler/pgo/pgo.gni")
 import("//build/config/features.gni")
 import("//build/config/locales.gni")
 import("//build/config/sanitizers/sanitizers.gni")
@@ -146,16 +145,6 @@ if (!is_android && !is_mac) {
       output_name = "chrome"
     }
 
-    if (!is_win || is_clang) {
-      # Normally, we need to pass specific flags to the linker to
-      # create an executable that gathers profile data. However, when
-      # using MSVC, we need to make sure we *don't* pass /GENPROFILE
-      # when linking without generating any code, or else the linker
-      # will give us fatal error LNK1264. So we add the PGO flags
-      # on all configurations, execpt MSVC on Windows.
-      configs += [ "//build/config/compiler/pgo:default_pgo_flags" ]
-    }
-
     # Because the sources list varies so significantly per-platform, generally
     # each platform lists its own files rather than relying on filtering or
     # removing unused files.
@@ -468,7 +457,6 @@ if (is_win) {
         configs -= [ "//build/config/win:default_incremental_linking" ]
         configs += [ "//build/config/win:no_incremental_linking" ]
       }
-      configs += [ "//build/config/compiler/pgo:default_pgo_flags" ]
     }
   }
   copy("copy_first_run") {